Comparison of Efficacy and Safety of Two Biphasic Defibrillators in Cardioversion of Atrial Fibrillation

Background: Biphasic truncated exponential (BTE) waveforms are standard for cardiac defibrillation and synchronized cardioversion up to date. BTE waveforms differ by design characteristics and technologies for pulse commutation (rectilinear, standard truncated exponential, pulsed). Clinical evaluation of BTE waveforms can be planned during cardioversion (CVS) as a well-established procedure of atrial fibrillation patients who are able to give consent and also present a more controlled population. Scarce studies have been found to present the relative efficacy and safety of different BTE waveforms during CVS. The validity of significantly deviating results of the pulsed waveform in one CVS study is questionable. Objective: To compare the CVS efficacy and safety two different biphasic defibrillators - a standard truncated exponential waveform and a pulsed biphasic waveform. Experimental design: Patients will be recruited at the Intensive Cardiology Care Unit (ICCU), Cardiology Clinic, University National Heart Hospital (NHH), Sofia, Bulgaria, underwent the pre-CVS medical exams and check for eligibility. All eligible patients will sign a written informed consent prior to the CVS and will receive the standard hospital procedures during CVS, accepted in the NHH, and approved by the NHH Local Ethic Committee. Atrial fibrillation patients will be alternatively randomized to CVS using one of the two defibrillators, following the same energy selection protocol in both defibrillators. The statistical power analysis will consider a non-inferiority comparison between the cumulative energy actually delivered by both defibrillators. The secondary CVS outcome measures are: the cumulative success rate (measured at 1 minute post-shock) and number of delivered shocks. Delivered energy will be measured during each shock with a dedicated pulse recording device (approved by the NHH Local Ethic Committee). Heart rhythm will be monitoring in continuously recorded peripheral ECG. Th